Have you ever wondered why we have the electrical power ratings for home, that we use to rate switches and sockets today? Well, if you do, we have some interesting answers for you.


Like many things, the standards used for rating electrical switches and wall sockets are also a legacy of the Britishers. In early years, electricity was utilized mainly for lighting and 2A or 5A circuits with two-pin plugs were used. Then, in 1934, the UK introduced new regulations (BS 546) which required an earth pin – hence three-pin plugs came into existence. Subsequently, new ampere sizes of 2, 5, 15 and 30 were also introduced for running heavy-duty electrical appliances like cookers and industrial equipment.


However, things did not stay as they were for long. After WWII, the electricals saw another revamp and all sockets were standardized on 13A. It was the nearest to a 3-kilowatt supply on 240 volts at that time. But the previous sockets also remained in use and can still be found in some places, finding specific use in things like theater lighting and mood lighting. The advancement of technology has also allowed companies to fit the 5A circuits in smaller 2A and 5A sockets.


The main reason why we see the current home and office circuits and socket designs standardized between 5A and 15A is because of the spectrum of options they can cover. At 240V, the 5A switches and socket allow you to run any appliance with up to 1kW load – which covers most of the lighting and home appliances. And, the 15A sockets can bear triple the load with up to 3kW capacity – which is more than enough to run any heavy-duty appliance made for home use. Many people argue for a 10A socket but the coverage provided by 5A and 15A sockets makes that argument redundant.


Since, the British Empire was quite large at the time of these changes in electrical systems, the legacy was inherited by almost all Commonwealth countries after de-colonisation. So, that is how the current electrical ratings got standardised across half-the-world.


Everyone is not using these standards

While the electrical standards we use in India (inherited from the UK) are widely used, they are not universal. Today, most of Europe, Africa, Asia, Australia, New Zealand and a large number of South American countries use a supply that is within 6% of 230V. In the UK and Australia, the nominal supply voltage is 230V +10%/−6% to accommodate the fact that most supplies there are still 240V.


On the other hand, the United States of America use a supply voltage of 120 volts +/- 6%. Japan, Taiwan, Saudi Arabia, North America, Central America and some parts of northern South America influenced by the US also use a voltage between 100V and 127V.


But, in general, the 230V standard has become so widespread that 230V equipment can be used in most parts of the world with specific adapters or by simply changing the equipment’s connection plug. The switches and sockets have also evolved in the process. New modular switch designs from brands like Honeywell support all kinds of adapter pins and plugs, providing universal connectivity.